Until recent years, bridge deck workers, along railways or the like, have not been required to use fall protection equipment.
Rescue of workers from a railway bridge has recently become a significant issue in view of movement to provide a higher degree of worker safety. In the past, A-frame type structures (bi-pods) have typically been used in cliff rescue to redirect a rope over an edge to reduce edge friction on that rope. These setups were often even improvised at the site.
More recently, as illustrated for example in U.S. Pat. No. 4,606,430 of Roby et al. and co-pending application Ser. No. 08/246,484 filed May 19 1994, fall protection anchors have been developed which secure to a rail of a railway. Such anchors are typically installed away from the bridge deck surface, because it is necessary to provide clearance or an envelope of safety for passing traffic.
Other references of general background interest relating to apparatus for moving or retrieving persons using a hoist arrangement include U.S. Pat. Nos. 4,589, 523 of Olson et al. issued May 20, 1986 and 5,147,013 of Olson et al. issued Sep. 13, 1992, and Canadian Patent Application No. 2,093,958 of Bell published Oct. 21, 1993.
If a worker, tethered to a rail fall protection anchor, falls off of the bridge so that that worker is suspended below the bridge deck, it becomes extremely desirable to provide a rescue system which will permit unobstructed hoisting of that worker, from a position beyond the end of the railway ties of the bridge. It is a primary object of the present invention to accomplish this task.